Seed bed mulches accomplish a number of functions. They protect the soil and seed from water and wind erosion, reduce evaporation from the soil surface, increase the humidity of the soil, moderate temperature fluctuations at the soil surface, and dissipate the energy of falling water droplets to decrease disturbance of the soil surface.
Such mulches are used in yard patch products which are sold at retail throughout the United States. The products are sold to home owners who use the products to re-establish turf grass in bare or thin areas. These products contain hammer milled paper fiber as the mulch. This mulch has a density of approximately 2.5 pounds per cubic foot. The products include loose seed and loose fertilizer which have been mixed into the paper mulch before packaging.
During shipment of the packaged product, however, due to the size and density differential between the seed and fertilizer on the one hand, and the fine paper mulch on the other hand, much of the seed and fertilizer falls out of the paper matrix to the bottom of the bag. When the product is used, this settling has a substantial effect on the seed and fertilizer application rate, which can lead to an unacceptable grass plant coverage rate. The typical application of this product covers the ground at a thickness of approximately one inch. The fibrous nature of the paper suspends the seed within the fiber mulch matrix. After application, the suspended seed absorbs water and germinates within the mulch, rather than on the ground. The roots of these new seedlings must then grow into the soil for the seed to be established. However, if the paper mulch is not kept damp at least until the seedling root is established in the soil, the seedlings will die. This factor also affects the plant coverage rate using the product.
Still another issue with this fine paper-based mulch turf grass patch product is that its relatively low density translates into increased packaging and shipping costs relative to the square feet of lawn which can be re-seeded. Also, the retailers must devote additional shelf space to the product, which in effect makes the product more expensive. Accordingly, this hammer milled paper based patch product is less than ideal.